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Cataplexy is a medical condition which often affects people who have narcolepsy, a disorder whose principal signs are EDS (Excessive Daytime Sleepiness), sleep attacks, sleep paralysis, hypnopompic hallucinations and disturbed night-time sleep. Cataplexy is sometimes confused with epilepsy, where a series of flashes or other stimuli cause superficially similar seizures.
The term cataplexy originates from the Greek kata, meaning down, and plexis, meaning a stroke or seizure.
- Head trauma
- Hypocretin deficiency
- Hypothalamus lesions
- Neurodegenerative diseases
- Niemann pick disease
- Sleep attacks
- Sleep paralysis
Causes by Organ System
|Chemical/Poisoning||No underlying causes|
|Dental||No underlying causes|
|Dermatologic||No underlying causes|
|Drug Side Effect||Modafinil, Provigil|
|Ear Nose Throat||No underlying causes|
|Endocrine||Niemann pick disease|
|Environmental||No underlying causes|
|Gastroenterologic||No underlying causes|
|Genetic||No underlying causes|
|Hematologic||No underlying causes|
|Iatrogenic||No underlying causes|
|Infectious Disease||No underlying causes|
|Musculoskeletal/Orthopedic||No underlying causes|
|Neurologic||Astrocytoma, Encephalitis, Glioblastoma, Glioma, Head trauma, Hydrocephalus, Hypnagogic hallucinations, Hypocretin deficiency, Hypothalamus lesions, Multiple sclerosis, Narcolepsy, Neurodegenerative diseases, Niemann pick disease, Sleep attacks, Sleep paralysis|
|Nutritional/Metabolic||No underlying causes|
|Obstetric/Gynecologic||No underlying causes|
|Oncologic||Astrocytoma, Glioblastoma, Glioma, Paraneoplasia syndrome, Subependynoma, Surgical tumor resection|
|Ophthalmologic||No underlying causes|
|Overdose/Toxicity||No underlying causes|
|Psychiatric||No underlying causes|
|Pulmonary||No underlying causes|
|Renal/Electrolyte||No underlying causes|
|Rheumatology/Immunology/Allergy||No underlying causes|
|Sexual||No underlying causes|
|Urologic||No underlying causes|
|Miscellaneous||No underlying causes|
Causes in Alphabetical Order
Cataplexy manifests itself as muscular weakness which may range from a barely perceptible slackening of the facial muscles to the dropping of the jaw or head, weakness at the knees, or a total collapse. Usually the speech is slurred, vision is impaired (double vision, inability to focus), but hearing and awareness remain normal. These attacks are triggered by strong emotions such as exhilaration, anger, fear, surprise, orgasm, awe, embarrassment and laughter.
Cataplexy may be partial or complete, affecting a range of muscle groups, from those controlling facial features to (less commonly) those controlling the entire body. 
- Arm weakness
- Sagging jaw
- Drooping head
- Slumping of the shoulders
- Slurred speech
- Generalized weakness
- Knee buckling
When cataplexy happens often, or cataplexy attacks make patients fall or drop things, it can have serious affects on normal activities. It can cause accidents and be embarrassing when it happens at work or with friends. For example, a narcoleptic may not pick up a baby because they are afraid they may drop them. 
Despite its relation to narcolepsy, in most cases, cataplexy must be treated differently and separate medication must be taken. For many years, cataplexy has been treated with tricyclic antidepressants such as imipramine, clomipramine or protriptyline. However these can have unpleasant side-effects and so have been generally replaced by newer drugs such as Effexor, a more recent antidepressant. Xyrem, the brand-name of the compound (sodium)gamma-Hydroxybutyrate GHB, has been shown to treat not only cataplexic attacks, but in narcoleptics, it has also been shown to significantly reduce daytime sleepiness. Monoamine oxidase inhibitors may be used to manage both cataplexy and the REM sleep-onset symptoms of sleep paralysis and hypnagogic hallucinations.
A person's efforts to stave off cataplectic attacks by avoiding these emotions may greatly diminish their lives, and they may become severely restricted emotionally if diagnosis and treatment is not begun as soon as possible. 
Cataplexy in severe cases can cause vital signs to be hard to detect without a continuous auditory pulse oximeter (a well-known heart monitor). As an anecdotal example, one Allison Burchell, a sufferer of severe Cataplexy, has been sent to the morgue three times.
- "Narcolepsy". Childhood Sleep Disorders. Armenian Medical Network. 2006. Retrieved 2007-09-19. Text " Thomas F. Anders, M.D. " ignored (help)
- "Cataplexy". Sleep Disorders - Cataplexy. 2007. Retrieved 2007-09-19.
- "Cataplexy Introduction for Patients". Jazz Pharmaceuticals, Inc. 2007. Retrieved 2007-09-19.
- Black J, Houghton WC (2006). "Sodium oxybate improves excessive daytime sleepiness in narcolepsy". Sleep. 29 (7): 939–46. PMID 16895262.
- "Narcolepsy and Cataplexy". NODSS Narcolepsy and Overwhelming Daytime Sleep Society of Australia. Retrieved 2007-09-19.
- "The woman who died three times". The Argus. 2000-10-18. Retrieved 2006-12-20.